Failure Analysis of Blister Packaging Camshaft

Project Relevance:

Packaging is one of the largest industry sectors in the world, worth $280 billion. Consumer healthcare packaging represents 4% ($11.2 billion) of the packaging industry. As drug manufacturers approach the 21st century, they face a number of challenges that packaging can help them meet. In this work camshaft under consideration operates forming die of a blister forming station at 45 cycles per minute. When forming die is in closed condition, operating load of the assembly is maximum i.e.19828N, and in open condition it takes only dead load i.e. 266N in opposite direction. Thus, camshaft is subjected to alternate tension and compression due to bending loads. The shaft fails after few cycles wherein PLC screen shows the number of cycles completed till failure. The aim of this project is to modify the shaft to withstand such an operational alternating loads which intern provides a high service warranty to the customer. This modification of the shaft done on relaxing the fillet radius. The shaft can be modified with help of changing its filet radius. For that as per reference paper shaft 30 mm diameter and 45 mm diameter with its filet radius is 0.5 mm and 4.5 mm respectively. FEA of that two diameters with changing filet radius . From this comparison best result diameter shaft manufactured and take experimental test. Before experimental, we analysis a various filet radius with 45 mm diameter for FEA is done.

Literature Review:

J. D. Chougule1, R. G. Todkar,[1] showed the influence of a cam shaft in the transmission system of a blister packaging machine used for packaging of tablets. It is observed that the cam shaft fails due fatigue loading into two pieces during operation. To find out cause of failure, a finite element analysis was carried out. Results of stress analysis reveal that the highest stressed area coincides with the fractured regions of the failure of the shaft. The theoretical stress fairly matches with the sub-model stress values. The failure analysis shows that the fatigue failure of the shaft is due to weak section at the step provided for cam shaft mount. To enhance service durability of the transmission system of Blister Packing Machine, stress concentration at cam step was modified and material with high service durability, mechanical characteristics such as fatigue strength, ultimate tensile strength, and fracture toughness was selected.

The possible reasons concept of the automobile diesel engine crankshaft failure i.e. operating sources, repairing sources and mechanical sources has been presented in detail by F. S. Silva [2] and observed that the crankshaft failure occurs due to small cracks which are developed as an effect of thermal fatigue loading substantial overheating during shaft grinding process.

Stuart H. Loewenthal [3] has studied the method of power shaft design which accounts for a variable amplitude loading histories and their effects on limited life design requirements considering the effects of combined bending and torsion loading and a number of service factors.

S. Abdullah et al. [4] discussed the technique of analysis is explain to assess a fatigue life of a shell structure under the variable loadings using finite element analysis technique for a simulation works and it is observed that constant amplitude predict a life larger as long as one predicted by variable amplitude tests. To enhance service durability of the transmission system of Blister Packing Machine, stress concentration at cam step was modified and material with high service durability, mechanical characteristics such as fatigue strength, ultimate tensile strength, and fracture toughness was selected.

Norman E. Dowling [5] has done comparison of the material test data with various approaches to estimating the effect of mean stress on stress life and strain life behavior is explained and seen that the walkers mean stress equation gives superior results.

M. Omid et al. [6] has performed fatigue analysis of the connecting rod to evaluate a critical point calculated stresses and displacements under maximum compression and tension loadings. The caustic method is very powerful method to detect the stress distribution for complicated mechanical elements such as connecting rod. By drilling several distributed small holes on the connecting rod, the caustic method can predict accurately the stress value at each hole position.

G. Wang [7] has introduced a crack modeling approach for the prediction of fatigue failure of the camshaft and which allows the calculation of an equivalent stress intensity factor enabling standard fracture mechanics methodology.

H. Bayrakceken [8] investigated the reason of failure analysis of a camshaft of an automobile engine is carried out by using scanning electron microscopy and chemical analysis of fractured camshaft material to assess the reasonableness of fracture

M. Shabanet. al.,M.I.Mohamed, A.E.Abuelezz, T Khalifa,(2013)[9], studied the stress pattern of crane hook in its loaded condition, a solid model of crane hook is prepared with the help of ABAQUS software. Real time pattern of stress concentration in 3D model of crane hook is obtained. The stress distribution pattern is verified for its correctness on an acrylic model of crane hook using shadow optical method (Caustic method) set up. By predicting the stress concentration area, the shape of the crane is modified to increase its working life and reduce the failure rates. The complete study is an initiative to establish a FEA procedure, by validating the results, for the measurement of stresses. For reducing the failures of hooks the estimation of stresses, their magnitudes and possible locations are very important. From the stress analysis, they have observed the cross section of max stress area. If the area on the inner side of the hook at the portion of max stress is widened then the stresses will get reduced. The caustic method is very powerful method to detect the stress distribution for complicated mechanical elements such as hooks. By drilling several distributed small holes on the hook, the caustic method can predict accurately the stress value at each hole position.

Om Parkash et. al. [10] had studied the Optimizing the Design of Connecting Rod under Static and Fatigue Loading. The main objective of their work was to re-optimize the existing design of connecting rod of universal tractor (U650) by changing some of the design variables. In their work, the model was developed, analyzed and designed using CATIA 19, PRO-E and ANSYS workbench v12. Optimization of connecting rod was done under same boundary and loading conditions for variation in the few stress and fatigue parameters i.e. stresses, weight, life, damage, bi-axiality indication and safety factor. Stress concentration coefficient was varied to obtain the maximum cycles condition. The critical regions under both static and fatigue analysis were identified and improved. The connecting rod was modeled and optimized for the reduced weight, improved life and manufacturability. The results obtained from performed analysis could be used to modify the design of existing connecting rod, so that better performance i.e. reduced inertia, fatigue life and manufacturability could be obtained under varying static and fatigue conditions.

A. A. Pandharabale, Asst. Prof. A. J. Rajguru,[11] The main objective of their paper was to design a model of dual worm system for optimal load lifting capacity, optimal factor of safety and optimal efficiency for reduced power consumption. They have derived the optimal power for individual motor and select the motor for the application so as to make the device compact. The experimental validation part of the lifting force developed by the dual worm system is validated using test-rig. Various characteristics graph were plotted like Torque Vs. Speed, Power Vs. speed, Power consumption of motor under rated load, Efficiency of system Vs. speed. They concluded that the torque increases with the decrease in the output speed, Graph of power output indicates a rising trend up to certain output speed and then slightly drops indicating that indicating that the device will slow down slightly if the load is increased.

A.S.Dhavale , V.R.Muttagi,[12] In four strokes engine one of the most important component is camshaft, such a important part and that over the years subject of extensive research. In this study, causes of fracture of camshaft are discuses. By using scanning electron microscopy and finite element analysis methods are used for fracture analysis of camshaft. It is seen that, The analyzed camshaft is fractured after a very short period of usage of the car. The failure is occurred as a sudden fracture at very close to journal location, where there is a stress concentration. The main reason of the fracture is determined as a casting defect. As the failure was related to a material production problem it is likely to affect more than one vehicle. So, the camshaft of vehicles manufactured from that particular series of camshaft should be replaced. Also, the non destructive testing procedures of the component supplier should also be improved as the defect can easily be detectable by standard non destructive techniques.

Zhiwei Yu, Xiaolei Xu,[13], A failure investigation has been conducted on a diesel-engine crankshaft used in a truck, which is made from 42CrMo forging steel. The crankshaft was nitrided. The fracture occurred in the web between the 2nd journal and 2nd crankpin. The depth of the nitrided layer in various regions of the crankshaft particularly in the fillet region close to the fracture was determined by SEM observation and micro-hardness (HV0.1) measurement, combined with nitrogen content analysis by EDAX. The mechanical properties of the crankshaft including tensile properties, marohardness (HB) and surface hardness (HV1) were evaluated. Fractographic studies indicate that fatigue is the dominant mechanism of failure of the crankshaft. The partial absence of the nitrided layer in the fillet region close to the fracture makes fatigue strength decrease to lead to fatigue initiation and propagation in the weaker region and premature fracture. The partial absence of the nitrided layer may result from over-grinding after nitriding. In order to prevent fatigue initiation in the fillet the final grinding has to be done carefully and the grinding amount controlled to avoid grinding down the nitrided layer.

Aim of Project:

The aim of this project is to modify the shaft to withstand such an operational alternating loads which intern provides a high service warranty to the customer. This modification of the shaft done on relaxing the fillet radius

Objectives of Dissertation:

1. To modify the shaft to withstand such an operational alternating loads which intern provides a high service warranty to the customer. For validation with finite element analysis (FEA) it is found that the stress is higher at the step, where failure was found in field.
2. To overcome problem of sub-modelling technique, in CREO-PARAMETRIC 2.0 is used. Sub-modeling is the technique of studying a local part of a model with a refined mesh, based on interpolation of the solution from an initial, global model onto appropriate parts of the boundary of the sub-model. The method is most useful when it is necessary
3. To obtain an accurate, detailed solution in the local region and the detailed modelling of that local region has negligible effect on the overall solution.

Research Methodology:

Literature Review

Study of Blister machine and its techniques.

Modeling of Camshaft

FEA of selected materials & cross-sections for particular load

Selection of best material & cross-section from FEA results

Manufacturing of camshaft from FEA result

Experimental testing

Comparison of experimental result with FEA results for given load

Conclusions

Experimental Setup:

Fig. 1: Experimental testing of camshaft on UTM

Results:

FEA results

Results can be obtained by FEA as well as Experiment.

Table 1 : Results of FEA

Diameter 30 mm 45 mm

Fillet Radius 0.5 mm 4.5 mm

Von-mises stress 120.27 Mpa 100.23 Mpa

Deformation 0.0070434 0.005869

After that, by FEA best result obtained, by taking fillet radius 4.5 mm. As the comparison of above result von-mises stresses is high at 30 mm diameter as compared to 45 mm diameter. This is also same as deformation, that means deformation is less at 45 mm diameter and it is more 30 mm diameter. Next step we want to check at 45 mm diameter, changing fillet radius and check out the results. And then this result compare to above table. Before that best result obtained at 45 mm diameter , so taking the dimensions and shaft is made on workshop. After the manufacturing of shaft experimental analysis is done on UTM. By using the strain gauge strain also calculated. In experimental analysis we can get the values of von-mises stress and deformation. After th values whuch are coming from the experiment , FEA is done . but in fea total load applied on shaft is 10 % reduced, because in real there is no possible to applied a load. So external weight is applied. Then the result comparison of experimental and FEA are given below,

Table 2 :Results of FEA

Optimised FEA

Diameter 45 45

Filet radius 4.5 4.5

Von-mises stress 103.87 100.23

Deformation 00020 000569

So, we take as 45 mm diameter and fillet radius takes 3 mm , 3.5 mm and 4 mm. and that obtained result by FEA is below table.

Table 3 : Results of FEA (with different filet radius)

Diameter 45 mm 45 mm 45 mm

Fillet Radius 3 mm 3.5 mm 4 mm

Von-mises stress 112.07 Mpa 107.52 Mpa 104.78 Mpa

Deformation 0.00656 0.006296 0.006136

After studying of all result, best result given by 45 mm diameter and its fillet radius 4.5 mm, so using this dimension camshaft is made. And this shaft using UTM stresses and deformation is calculated.

After that calculating the life cycle for 45 mm diameter and its different filet radius. Also comparing all result diameter 45 mm and its filet radius 4.5 mm gives good result as compare to all.

Table 4 : Results of FEA life cycle (with different filet radius)

Diameter 45 mm 45 mm 45 mm 45 mm

Fillet Radius 3 mm 3.5 mm 4 mm 4.5 mm

Life cycle 2.106e5 2.802e5 3.2499e5 4.1978e5

As the above result shows the, number of cycles increases, with decreasing the stress.

Conclusion:

This chapter consist the concluding remarks on current research work. The experimentation performed on Universal testing machine. The analysis result was also done in previous chapter result and discussion. The concluding remarks on experimentation and its results are covered and also necessary outcomes are represented in this chapter. The future scope for this project is also stated at the end of this chapter. The outcomes from the current research work are as follows;

From results of finite element analysis it is observed that the maximum stress value is within the safety limit. There is a great potential to optimize, this safety limit which can be done by removing material from low stressed region thus optimizing its weight without affecting its structural behavior. The maximum displacement value is also very less. So, the material from low stressed region is can be removed without affecting its strength and is within the yield strength.

Von-mises stress found on existing (120.27 MPa) and optimized (100.23 MPa) components are within the material yield strength.

Deflection measured and found on existing (0.0070434mm) and optimized (0.00569mm) model is very less.

Project Expenditure:

Sr. No. Name of Equipment Qty. Approx. Cost

(INR)

Material for Specimen 01 2000 = 00

Raw Material Cutting and machining 01 5800 = 00

Bracket Joining 04 1000 = 00

Experimentation and Lab charges ---- 8000 = 00

Miscellaneous Expenses --- 4000 = 00

Total Expenditure: Rs. 20800 = 00

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